Bus bar

Abstract

To provide a bus bar that can enhance heat dissipation effect while suppressing an increase in weight.SOLUTION: A bus bar 1 includes a pair of connection portions 111 connected to a terminal T, a conductor portion 112 between the pair of connection portions 111, and a heat dissipation fin 12 protruding from the conductor portion 112. An area of a cross section perpendicular to the current path in a first region A1 in which the heat dissipation fin 12 is provided is smaller than an area of a cross section perpendicular to the current path in a second region A2 outside the first region A1 and including the connection portions 111.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bus bar. [Background technology]

[0002] A bus bar that connects the terminals of adjacent secondary batteries in a battery pack is known to have a plate-shaped base portion with through holes formed therein through which the terminals are inserted, and a plurality of heat dissipation fins that are provided perpendicular to the base portion (see, for example, Patent Document 1). In the bus bar described in Patent Document 1, the heat dissipation fins are provided on the base portion, which increases the surface area and cross-sectional area of ​​the bus bar and improves the heat dissipation effect of the bus bar. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-105674 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the busbar described in Patent Document 1 has a configuration in which heat dissipation fins are added to the base portion, so there is a trade-off between heat dissipation effect and weight, and while the heat dissipation effect is improved, the weight is also increased.

[0005] In view of the above circumstances, an object of the present invention is to provide a bus bar that can enhance heat dissipation effect while suppressing an increase in weight. [Means for solving the problem]

[0006] The busbar of the present invention comprises a pair of connection portions connected to a connection object, a conductor portion between the pair of connection portions, and a heat dissipation fin protruding from the conductor portion, wherein the cross-sectional area perpendicular to the current path in a first region in which the heat dissipation fin is provided is smaller than the cross-sectional area perpendicular to the current path in a second region outside the first region that includes the connection portions. [Effects of the Invention]

[0007] According to the present invention, it is possible to improve the heat dissipation effect while suppressing an increase in weight. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a bus bar according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing the bus bar shown in FIG. [Figure 3] FIG. 3 is a perspective view showing a connection portion of the bus bar shown in FIG. [Figure 4] FIG. 4 is a perspective view showing a bus bar according to a first comparative example. [Figure 5] FIG. 5 is a cross-sectional view showing a bus bar according to a second comparative example. [Figure 6] FIG. 6 is a diagram showing the results of a simulation of the saturation temperature of the bus bar according to the first comparative example shown in FIG. [Figure 7] FIG. 7 is a diagram showing the results of a simulation of the saturation temperature of the bus bar according to the second comparative example shown in FIG. [Figure 8] FIG. 8 is a diagram showing the results of a simulation of the saturation temperature of a busbar that has the same shape and dimensions as the busbar according to the embodiment shown in FIG. 1 but whose surface is not anodized. [Figure 9] FIG. 9 is a diagram showing the results of a simulation of the saturation temperature of the bus bar according to the embodiment shown in FIG. [Figure 10] FIG. 10 is a perspective view showing a bus bar according to another embodiment of the present invention. [Figure 11]FIG. 11 is a graph showing the results of a simulation of the saturation temperatures of the busbar shown in FIG. 10 and the busbar according to the first comparative example shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments described below, and the embodiments described below can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments described below, some components are omitted from illustration and description, but for the details of the omitted technologies, publicly known or well-known technologies are applied as appropriate within the scope of not causing any contradictions with the content described below.

[0010] Fig. 1 is a perspective view showing a busbar 1 according to one embodiment of the present invention. The busbar 1 shown in this figure is a conductor that connects terminals T of adjacent secondary batteries in a battery pack mounted on an electrically powered vehicle such as an electric vehicle or a hybrid vehicle, and a high-voltage, large current flows through the busbar when energized. Note that applications of the busbar 1 are not limited to secondary batteries for electrically powered vehicles, and may also include distribution boards, control panels, etc.

[0011] The busbar 1 is an aluminum casting with an anodized surface, and includes a rectangular plate-shaped base portion 11 and a plurality of heat dissipation fins 12 that are integral with the base portion 11. The base portion 11 includes a pair of connection portions 111 and a conductor portion 112 between the pair of connection portions 111. The conductor portion 112 is a portion that extends between the pair of connection portions 111, and each connection portion 111 is provided at an end portion in the longitudinal direction of the busbar 1. In the busbar 1, a current flows along the longitudinal direction of the busbar 1. In other words, the current path of the busbar 1 extends along the longitudinal direction of the busbar 1.

[0012] The connection portion 111 is a rectangular plate-shaped portion that comes into contact with the terminal T of the secondary battery, and is relatively thicker than the conductor portion 112. In this embodiment, the connection portion 111 has a thickness of 7 mm and a width (dimension in a direction perpendicular to the current path) of 20 mm. The thickness of the connection portion 111 is preferably 5 mm or more and 10 mm or less, and the width of the connection portion 111 is preferably 10 mm or more and 30 mm or less.

[0013] Fig. 2 is a cross-sectional view of the busbar 1 shown in Fig. 1. This figure shows a cross section of the busbar 1 taken at a longitudinal intermediate portion along a direction perpendicular to the longitudinal direction (current path).

[0014] 2, the thickness of the conductor portion 112 is relatively smaller than the thickness of the connection portion 111. The heat dissipation fins 12 protrude from one surface of the conductor portion 112 in a direction perpendicular to the surface. In this embodiment, the thickness of the conductor portion 112 is 3.7 mm, and the width of the conductor portion 112 (the dimension in the direction perpendicular to the current path) is 20 mm. The thickness of the conductor portion 112 is preferably 1 mm or more and 5 mm or less, and the width of the conductor portion 112 is preferably 10 mm or more and 30 mm or less.

[0015] A plurality of heat dissipation fins 12 (three in this embodiment) are arranged in parallel at equal intervals in the width direction of the plate surface (direction perpendicular to the current path) on one plate surface of the conductor portion 112, and extend along the longitudinal direction of the plate surface. As shown in FIG. 1 , each heat dissipation fin 12 is formed in a rectangular plate shape and extends from the boundary between the conductor portion 112 and one connection portion 111 to the boundary between the conductor portion 112 and the other connection portion 111. In this embodiment, the height (width) of each heat dissipation fin 12 is 20 mm, and the plate thickness of each heat dissipation fin 12 is 3.7 mm. The height of each heat dissipation fin 12 is preferably 10 mm or more and 30 mm or less, and the plate thickness of each heat dissipation fin 12 is preferably 1 mm or more and 5 mm or less.

[0016] A step is formed at the boundary between one plate surface of conductor portion 112 and one plate surface of connection portion 111, and the other plate surface of conductor portion 112 and the other plate surface of connection portion 111 are flush with each other without any step. The other plate surface of connection portion 111 is in contact with one surface of terminal T (see FIG. 1).

[0017] In this embodiment, the terminal T is a female terminal, and a screw hole (not shown) into which a bolt (not shown) is fastened is formed in the terminal T. On the other hand, the connection portion 111 is formed with a through hole 111A into which the bolt is inserted, and the connection portion 111 and the terminal T are fastened by the bolt. Note that if the terminal T is a male terminal, a bolt (not shown) protruding from the terminal T is inserted into the through hole 111A, and the connection portion 111 and the terminal T are fastened by the bolt and a nut (not shown).

[0018] Here, the cross-sectional area (hereinafter referred to as the cross-sectional area) of the busbar 1 in a direction perpendicular to the current path differs between the first region A1 where the heat dissipation fins 12 are provided and the second region A2 where the heat dissipation fins 12 are not provided. The cross-sectional area of ​​the first region A1 is smaller than the cross-sectional area of ​​the second region A2. In this embodiment, the region formed by the conductor portion 112 and the heat dissipation fins 12 is the first region A1, and the region formed only by the connection portion 111 is the second region A2.

[0019] In this embodiment, the cross-sectional area of ​​the first region A1 is 100 mm 2 whereas the cross-sectional area of ​​the second area A2 is 140 mm 2 The cross-sectional area of ​​the first region A1 is the sum of the cross-sectional area of ​​the conductor portion 112 and the cross-sectional area of ​​the heat dissipation fins 12.

[0020] 3 is a perspective view showing connection portion 111 of busbar 1 shown in FIG. 1. The other surface of connection portion 111 is surface 111B (hereinafter referred to as contact surface) that comes into contact with terminal T, and contact surface 111B is not anodized. This ensures electrical continuity between contact surface 111B of connection portion 111 and terminal T. In contrast, the entire surface of connection portion 111 other than contact surface 111B, the entire surface of conductor portion 112, and the entire surface of each heat dissipation fin 12 are anodized. This ensures insulation of the surface of busbar 1 other than contact surface 111B. Furthermore, the increased emissivity of the surface of busbar 1 enhances the effect of natural cooling by radiation (cooling in a windless environment without forced wind from outside).

[0021] Here, the amount of heat dissipated by radiation is defined by the following formula (1) in accordance with the Stefan-Boltzmann law: According to the Stefan-Boltzmann law, the higher the emissivity, the greater the heat dissipation effect by radiation.

number

[0022] Generally, metals have a low emissivity ε, making it difficult to enhance the heat dissipation effect by radiation. Therefore, in this embodiment, busbar 1 is made of cast aluminum, the surface area is increased by heat dissipation fins 12, and the entire surface of busbar 1 except for contact surface 111B is anodized to increase the emissivity ε and enhance the heat dissipation effect by radiation.

[0023] FIG. 4 is a perspective view showing a busbar 1' according to a first comparative example. As shown in this figure, the busbar 1' according to the first comparative example is a plate-shaped conductor with a uniform thickness, and is not provided with heat dissipation fins 12. This busbar 1' is a long rectangular conductor with a thickness of 7 mm and a width of 20 mm, and is made of aluminum casting, as in the above embodiment. The cross-sectional area of ​​the busbar 1' is 140 mm 2The surface of the bus bar 1' according to the first comparative example is not anodized.

[0024] FIG. 5 is a cross-sectional view showing a busbar 1" according to a second comparative example. As shown in this figure, the busbar 1" according to the second comparative example is an aluminum casting including a rectangular, plate-shaped base 11" with a uniform thickness and a plurality of heat dissipation fins 12 provided on one surface of the base 11". As in the above embodiment, the plurality of heat dissipation fins 12 are arranged in parallel at equal intervals in the width direction of one surface of the base 11" and extend along the longitudinal direction of the one surface. The thickness of the base 11" is 7 mm, the width of the base 11" is 20 mm, the height of the heat dissipation fins 12 is 20 mm, and the thickness of the heat dissipation fins 12 is 3.7 mm. Note that the surface of the busbar 1" according to the second comparative example is not anodized.

[0025] FIG. 6 is a diagram showing the results of a simulation of the saturation temperature (temperature in a thermally saturated state) of the busbar 1′ according to the first comparative example shown in FIG. 4. FIG. 7 is a diagram showing the results of a simulation of the saturation temperature of the busbar 1″ according to the second comparative example shown in FIG. 5. FIG. 8 is a diagram showing the results of a simulation of the saturation temperature of a busbar 1A that has the same shape and dimensions as the busbar 1 according to the embodiment shown in FIG. 1 but whose surface is not anodized.

[0026] In the simulations shown in Figures 6 to 8, the saturation temperature when a current of 450 A is passed through busbars 1', 1", and 1 A in an environment with an air temperature of 20°C was analyzed using cooling simulation software for electronic components (Ansys (registered trademark) Icepak).In Figures 6 to 8, the temperature is shown as concentration.Note that the concentration increases as the temperature increases.

[0027] The simulation results shown in FIG. 6 confirmed that the saturation temperature of the busbar 1' according to the first comparative example was 149.6°C. The simulation results shown in FIG. 7 confirmed that the saturation temperature of the busbar 1" according to the second comparative example was 107.9°C. The simulation results shown in FIG. 8 confirmed that the saturation temperature of a busbar 1A that has the same shape and dimensions as the busbar 1 according to the embodiment shown in FIG. 1 but is not anodized was 131.7°C, which is approximately 18°C ​​lower than that of the busbar 1' according to the first comparative example.

[0028] Here, the cross-sectional area of ​​the busbar 1 according to the embodiment shown in FIG. 2 and the cross-sectional area of ​​the busbar 1′ according to the first comparative example (140 mm 2 6 and 8, it was confirmed that the busbar 1A, which has the same shape and dimensions as the busbar 1 according to the embodiment but is not anodized, can achieve a weight reduction of approximately 30% and a saturation temperature reduction of approximately 18°C ​​compared to the busbar 1' according to the first comparative example.

[0029] Fig. 9 is a diagram showing the results of a simulation of the saturation temperature of the busbar 1 according to the embodiment shown in Fig. 1. In the simulation shown in Fig. 9, the saturation temperature when a current of 450 A flows through the busbar 1 in an environment with an air temperature of 20°C was analyzed using the cooling simulation software for electronic components. In Fig. 9, the temperature is represented by concentration. Note that the concentration increases as the temperature increases.

[0030] In the simulation shown in Fig. 9, the saturation temperature of busbar 1 in which the entire surface except for contact surface 111B is anodized was analyzed. In the simulation shown in Fig. 9, the emissivity ε of busbar 1 was set to 0.9. In contrast, in the simulation shown in Fig. 8, the emissivity ε of busbar 1A was set to 0.04. The conditions for the simulations shown in Fig. 8 and Fig. 9 are the same except for the emissivity ε.

[0031] The simulation results shown in Fig. 9 confirmed that the saturation temperature of the busbar 1 in which the entire surface except for the contact surface 111B was anodized was 91.2°C. Furthermore, the simulation results shown in Figs. 8 and 9 confirmed that the saturation temperature was reduced by approximately 40°C by increasing the emissivity ε by anodizing the entire surface except for the contact surface 111B.

[0032] As described above, in the busbar 1 according to this embodiment, the area of ​​the cross section perpendicular to the current path in the first region A1 where the heat dissipation fins 12 are provided is smaller than the area of ​​the cross section perpendicular to the current path in the second region A2 outside the first region A1 and including the connection portion 111. This makes it possible to increase the heat dissipation effect of the busbar 1 by increasing the surface area with the heat dissipation fins 12 while suppressing an increase in the weight of the busbar 1.

[0033] Furthermore, in busbar 1 according to this embodiment, pair of connecting portions 111, conductor portion 112, and heat dissipation fins 12 are made of aluminum, and the surfaces of conductor portion 112 and heat dissipation fins 12 are anodized. This not only increases the surface area of ​​heat dissipation fins 12, but also increases the emissivity ε of busbar 1, further improving the heat dissipation effect of busbar 1.

[0034] Furthermore, in the busbar 1 according to this embodiment, the surfaces of the pair of connecting portions 111 are anodized except for contact surfaces 111B with the terminals T. This makes it possible to increase the emissivity ε of the busbar 1 while ensuring electrical continuity between the busbar 1 and the terminals T.

[0035] Furthermore, in the busbar 1 according to this embodiment, the pair of connecting portions 111 and the conductor portion 112 are formed in a plate shape, and the plate thickness of the conductor portion 112 is smaller than the plate thickness of the pair of connecting portions 111. As a result, the cross-sectional area of ​​the conductor portion 112 in a direction perpendicular to the current path is smaller than the cross-sectional area of ​​the pair of connecting portions 111 in a direction perpendicular to the current path, thereby realizing a reduction in the weight of the busbar 1.

[0036] Fig. 10 is a perspective view showing a busbar 2 according to another embodiment of the present invention. The busbar 2 shown in this figure differs from the busbar 1 according to the embodiment shown in Fig. 1 in the configuration of the connection portions 211, 111. Note that the same components as those in the embodiment shown in Fig. 1 are denoted by the same reference numerals, and the description of the embodiment shown in Fig. 1 is incorporated herein.

[0037] 10, in the busbar 2 according to this embodiment, the connection portion 211 is formed in a U-shape. The connection portion 211 includes a pair of connection portions 111 and a joining portion 211B that joins the pair of connection portions 111. The pair of connection portions 111 face each other.

[0038] The terminal T is inserted between the pair of connecting portions 111 and fitted with the pair of connecting portions 111. A through hole (not shown) through which a bolt (not shown) is inserted is formed in the terminal T, and the connecting portion 211 and the terminal T are fastened together by the bolt inserted into the through hole 111A and the through hole of the terminal T and a nut (not shown) screwed onto the bolt.

[0039] The plate thickness of the pair of connecting portions 111 is greater than the plate thickness of the conductor portion 112. Furthermore, the contact surfaces of the pair of connecting portions 111 with the terminal T are not anodized, whereas the entire surface of the bus bar 2 except for the contact surfaces with the terminal T is anodized.

[0040] Fig. 11 is a graph showing the results of a simulation of the temperatures of the busbar 2 shown in Fig. 10 and the busbar 1' according to the first comparative example shown in Fig. 4. In this simulation, the temperatures when a current of 800 A was passed through the busbars 2 and 1' for 1200 seconds in an environment with an air temperature of 20°C were analyzed using the cooling simulation software for electronic components.

[0041] The simulation results shown in FIG. 11 confirm that the busbar 2 shown in FIG. 10 has a higher temperature suppression effect than the busbar 1′ according to the first comparative example shown in FIG.

[0042] The present invention has been described above based on the above embodiment, but the present invention is not limited to the above embodiment, and modifications may be made to the above embodiment within the scope of the spirit of the present invention, or publicly known or well-known technologies may be combined as appropriate.

[0043] For example, in the above embodiment, the first region A1 where the heat dissipation fins 12 are provided is a region that includes the entire conductor portion 112, but there may be a region where the heat dissipation fins 12 are not provided in the conductor portion 112. Also, in the above embodiment, the second region A2 that is outside the first region A1 and includes the connection portion 111 is only a region of the connection portion 111, but a portion of the conductor portion 112 may be included in the second region A2. [Explanation of symbols]

[0044] 1: Busbar 2: Busbar 12: Heat dissipation fin 111: Connection part 111B: Contact surface 112: Conductor part 211: Connection part A1: 1st area A2:Second area T: Terminal (connection object)

Claims

1. a pair of connection parts to be connected to the connection object; a conductor portion between the pair of connection portions; a heat dissipation fin protruding from the conductor portion; Equipped with The area of ​​a cross section perpendicular to the current path in a first region where the heat dissipation fins are provided is smaller than the area of ​​a cross section perpendicular to the current path in a second region outside the first region and including the connection portion. Busbar.

2. the pair of connecting portions, the conductor portion, and the heat dissipation fins are made of aluminum, The bus bar according to claim 1 , wherein the surfaces of the conductor portion and the heat dissipation fins are anodized.

3. The bus bar according to claim 2 , wherein surfaces of the pair of connecting portions excluding surfaces that come into contact with the connection objects are anodized.

4. The pair of connecting portions and the conductor portion are formed in a plate shape, The bus bar according to claim 1 or 2, wherein the conductor portion has a thickness smaller than that of the pair of connecting portions.

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